Pick: Difference between revisions

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{{Built-in|Pick|⊃}} is a [[dyadic]] [[primitive function]] which performs deep [[indexing]] on a possibly [[nested array]]. Pick allows to extract a value through multiple layers of nesting in a single function application. Pick shares the [[glyph]] <source lang=apl inline>⊃</source> with [[First]] or [[Mix]] depending on the dialect.
{{Built-in|Pick|⊃}} is a [[dyadic]] [[primitive function]] which performs deep [[indexing]] on a possibly [[nested array]]. Pick allows to extract a value through multiple layers of nesting in a single function application. Pick uses the [[Right Shoe]] glyph.


== Examples ==
== Examples ==


The left [[argument]] X must be a [[vector]] where each element of X specifies the multi-dimensional [[index]] at each layer of the right argument Y. The result of <source lang=apl inline>X⊃Y</source> is the item of Y at the location specified by X.
The left [[argument]] X must be a [[scalar]] or [[vector]] where each element of X specifies the multi-dimensional [[index]] at each layer of the right argument Y. The result of <syntaxhighlight lang=apl inline>X⊃Y</syntaxhighlight> is the item of Y at the location specified by X.


<source lang=apl>
<syntaxhighlight lang=apl>
       ⎕←G←2 3⍴('ABC' 1)('DEF' 2)('GHI' 3)('JKL' 4)('MNO' 5)('PQR' 6)
       ⎕←G←2 3⍴('ABC' 1)('DEF' 2)('GHI' 3)('JKL' 4)('MNO' 5)('PQR' 6)
┌───────┬───────┬───────┐
┌───────┬───────┬───────┐
Line 24: Line 24:
       ((2 1)1 2)⊃G
       ((2 1)1 2)⊃G
K
K
</source>
</syntaxhighlight>
 
== See also ==
* [[Index (function)]]
* [[Bracket indexing]]
* [[Select]]


== External links ==
== External links ==
Line 30: Line 35:
=== Documentation ===
=== Documentation ===


* [http://help.dyalog.com/latest/#Language/Primitive%20Functions/Pick.htm Dyalog]
* [https://help.dyalog.com/latest/#Language/Primitive%20Functions/Pick.htm Dyalog]
* [http://microapl.com/apl_help/ch_020_020_610.htm APLX]
* [http://microapl.com/apl_help/ch_020_020_610.htm APLX]


{{APL built-ins}}[[Category:Primitive functions]]
{{APL built-ins}}[[Category:Primitive functions]]

Latest revision as of 15:20, 8 November 2022

⊃

Pick (⊃) is a dyadic primitive function which performs deep indexing on a possibly nested array. Pick allows to extract a value through multiple layers of nesting in a single function application. Pick uses the Right Shoe glyph.

Examples

The left argument X must be a scalar or vector where each element of X specifies the multi-dimensional index at each layer of the right argument Y. The result of X⊃Y is the item of Y at the location specified by X. 

      ⎕←G←2 3⍴('ABC' 1)('DEF' 2)('GHI' 3)('JKL' 4)('MNO' 5)('PQR' 6)
┌───────┬───────┬───────┐
│┌───┬─┐│┌───┬─┐│┌───┬─┐│
││ABC│1│││DEF│2│││GHI│3││
│└───┴─┘│└───┴─┘│└───┴─┘│
├───────┼───────┼───────┤
│┌───┬─┐│┌───┬─┐│┌───┬─┐│
││JKL│4│││MNO│5│││PQR│6││
│└───┴─┘│└───┴─┘│└───┴─┘│
└───────┴───────┴───────┘
      (⊂2 1)⊃G
┌───┬─┐
│JKL│4│
└───┴─┘
      ((2 1)1)⊃G
JKL
      ((2 1)1 2)⊃G
K

See also

External links

Documentation


APL built-ins [edit]
Primitives (Timeline) Functions
Scalar
Monadic Conjugate ∙ Negate ∙ Signum ∙ Reciprocal ∙ Magnitude ∙ Exponential ∙ Natural Logarithm ∙ Floor ∙ Ceiling ∙ Factorial ∙ Not ∙ Pi Times ∙ Roll ∙ Type ∙ Imaginary ∙ Square Root ∙ Round
Dyadic Add ∙ Subtract ∙ Times ∙ Divide ∙ Residue ∙ Power ∙ Logarithm ∙ Minimum ∙ Maximum ∙ Binomial ∙ Comparison functions ∙ Boolean functions (And, Or, Nand, Nor) ∙ GCD ∙ LCM ∙ Circular ∙ Complex ∙ Root
Non-Scalar
Structural Shape ∙ Reshape ∙ Tally ∙ Depth ∙ Ravel ∙ Enlist ∙ Table ∙ Catenate ∙ Reverse ∙ Rotate ∙ Transpose ∙ Raze ∙ Mix ∙ Split ∙ Enclose ∙ Nest ∙ Cut (K) ∙ Pair ∙ Link ∙ Partitioned Enclose ∙ Partition
Selection First ∙ Pick ∙ Take ∙ Drop ∙ Unique ∙ Identity ∙ Stop ∙ Select ∙ Replicate ∙ Expand ∙ Set functions (Intersection ∙ Union ∙ Without) ∙ Bracket indexing ∙ Index ∙ Cartesian Product ∙ Sort
Selector Index generator ∙ Grade ∙ Index Of ∙ Interval Index ∙ Indices ∙ Deal ∙ Prefix and suffix vectors
Computational Match ∙ Not Match ∙ Membership ∙ Find ∙ Nub Sieve ∙ Encode ∙ Decode ∙ Matrix Inverse ∙ Matrix Divide ∙ Format ∙ Execute ∙ Materialise ∙ Range
Operators Monadic Each ∙ Commute ∙ Constant ∙ Replicate ∙ Expand ∙ Reduce ∙ Windowed Reduce ∙ Scan ∙ Outer Product ∙ Key ∙ I-Beam ∙ Spawn ∙ Function axis ∙ Identity (Null, Ident)
Dyadic Bind ∙ Compositions (Compose, Reverse Compose, Beside, Withe, Atop, Over) ∙ Inner Product ∙ Determinant ∙ Power ∙ At ∙ Under ∙ Rank ∙ Depth ∙ Variant ∙ Stencil ∙ Cut ∙ Direct definition (operator) ∙ Identity (Lev, Dex)
Quad names Index origin ∙ Comparison tolerance ∙ Migration level ∙ Atomic vector
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